Conventionally, a technique of finding features of a subject specified by a camera user (hereinafter “user”) or a subject specified by an imaging apparatus based on predetermined conditions, these subject being hereinafter referred to as “main subject,” and estimating the area in image data where the main subject is present based on the features, is known. Particularly, the process of finding in a serial manner the area where the main subject is present in moving image data comprising image data that is inputted on a continuous basis, is carried out to follow the moving main subject, and therefore is often referred to as “tracking process” or “chasing process.” Note that the process of following a main subject in moving image data will be referred to as “tracking” with the present invention.
Various types of imaging apparatuses that find the position of a main subject by such a tracking process and that performs shooting control for shooting the main subject adequately, including focus control for focusing on the main subject, exposure control for adjusting the color value of the main subject to an adequate level and framing control for adjusting the shooting range, are proposed (for example, see Patent Literature 1). Usually, in framing control, panning, tilting and zooming are performed such that the main subject is placed in the center of the screen.
FIG. 1 is a flowchart showing a process of switching between two subject detection modes in an imaging apparatus with an automatic tracking function disclosed in Patent Literature 1.
In FIG. 1, after the imaging apparatus is powered on, upon selecting shooting mode in step S1, the user is able to use an operating means equipped in the imaging apparatus to select whether to operate the imaging apparatus in normal mode in step S2 or operate the imaging apparatus in tracking mode in step S3. It is possible to execute this selection when necessary before the imaging apparatus is powered off in step S4.
The imaging apparatus disclosed in Patent Literature 1 that has such a function of selecting operation modes, has a subject detecting section and a switching section. The subject detecting section can detect a main subject from an image that is taken. The switching section switches between normal mode and tracking mode. In normal mode, the subject detecting section detects the main subject from the image that is taken. In tracking mode, the subject detecting section detects the main subject by targeting a recognition area, which is part of an image that is taken.
Normal mode refers to mode for, for example, performing a face detection process to detect one or more faces from an image that is taken. Tracking mode refers to mode for, for example, detecting a face in a recognition area in which the default state of a recognition area is set in the center of an image and then changing the position of the recognition area to follow the position of the face detected in the recognition area. In normal mode, faces having features registered in an imaging apparatus and faces of higher priority to which weight has been assigned based on information about the size, position and so on are automatically detected. On the other hand, in tracking mode, a face that is not registered yet in an imaging apparatus, and a face of a high interest to users although its priority is low, can be detected.
The imaging apparatus disclosed in Patent Literature 1 is configured to use results of subject detection in automatic focus adjustment control and automatic exposure control in any mode of normal mode and tracking mode. Further, the imaging apparatus disclosed in Patent Literature 1 has a pan head that supports this imaging apparatus, and the result of subject detection is used to control this pan head based on the position in the image taken where the subject is detected, and is used to perform framing control such that the main subject is placed in the center of the screen.